The present application discloses a method and apparatus for extracting association rules from data having two or more numeric attributes and a true-false attribute, and for presenting the rules in an easily understandable form. The method comprises the steps of: (i) storing numbers u(i,j) and v(i,j) of data in each pixel whose true-false attribute is true, so as to correspond to each pixel in a plane; (ii) inputting a condition .theta.; (iii) segmenting from the plane a rectilinear region S of the pixels to maximize the equation ##EQU1## ;and (iv) outputting data included in the segmented rectilinear region S. The invention also allows regions to be derived which satisfy a desired support maximization rule, confidence maximization rule, optimized entropy rule, and optimized interclass variance rule.